Determination of oxalate based on its enhancing effect on the oxidation of Mn(II) by periodate

A new kinetic spectrophotometric method for the determination of oxalate has been described, based on its enhancing effect on the oxidation of Mn(II) to MnO4−, which is measured at 525 nm, by potassium periodate. Under the optimum conditions of 20 μg ml−1 Mn(II) in MnSO4·H2O/0.015 mol l−1 H3PO4/0.013 mol l−1 sodium acetate and 3×10−3 mol l−1 KIO4 at 35 °C, calibration graphs in the range of 0.05–1.25 and 0.05–1.75 μg ml−1 oxalate concentration were obtained with detection limits of 27 and 5 ng ml−1 by the fixed time and the induction period methods, respectively. No serious interference was identified. The proposed method is simple, inexpensive, sensitive and accurate. The applicability of the method was demonstrated by the determination of the oxalate in spinach and urine samples.